As set forth in Gettys et al. U.S. Pat. No. 4,882,301, glass sections for automobiles, trucks or other automotive conveyance devices, including, for example, side and rear lights or windows, and windshields, are many times produced with varying degrees of curvature as opposed to flat, planar surfaces. If a curvature is desired in a given section, it is heated to a temperature in the vicinity of about 1300.degree. F., at which point it is ready to be subjected to a bending or curving stress employing any number of suitable molding or pressing techniques. The section of glass, during the bending operation, maintains sufficient surface hardness such that the press head of the equipment employed to bend or curve the glass or the vacuum head utilized to pick up and transport the section of glass does not disturb the surface of the glass with which it contacts.
Automotive manufacturers have found that the appearance of a section of glass is greatly enhanced by applying a relatively narrow, opaque, colored band or border around the edge of the section of glass, along the inner surface. This band, which frames the edge of the inner surface of the section of glass, may vary anywhere from about an inch to about six inches in width. By blocking the passage of sunlight this band also serves to prevent the degradation of underlying adhesives by U.V. radiation.
Because of its relative durability, it has been found that the colored band is best produced through the use of a composition that forms an enamel during the heating and forming of the section of glass. As discussed in U.S. Pat. No. 4,882,301, preferably the composition which is utilized to form the enamel is such that it prevents the press or vacuum head of the equipment utilized to bend or transport the section of glass from sticking to the enamel and/or disturbing the surface of the enamel.
As set forth in U.S. Pat. No. 4,882,301 there are essentially two ways to help prevent the press or vacuum head from sticking to the glass enamel. More particularly, either a large amount of precursors of Zn.sub.2 SiO.sub.4 or Cd.sub.2 SiO.sub.4 may be incorporated into the composition utilized to produce the enamel (i.e., large amounts of ZnO, SiO.sub.2 or CdO may be included in the composition), or a significant amount of crystalline Zn.sub.2 SiO.sub.4 or Cd.sub.2 SiO.sub.4 may be utilized in the composition (i.e., from about 25 percent by weight to about 50 percent by weight Cd.sub.2 SiO.sub.4 or Zn.sub.2 SiO.sub.4 may be included in the composition). Successful results have been obtained when using CdO as a precursor as disclosed in U.S. Pat. No. 4,882,301. However, in light of recent environmental restrictions and concerns, cadmium is sometimes not preferred for use in industry. Unfortunately, when zinc is substituted for the cadmium, the results have been less than desirable. Specifically, when either significant amounts of the precursors of Zn.sub.2 SiO.sub.4 or crystalline Zn.sub.2 SiO.sub.4 itself have been substituted for the cadmium, the melting temperature of the composition has been adversely affected and/or the vacuum or press head has stuck to and/or visually impaired the surface of the enamel.